Parathyroid adenomas following irradiation

Two Cases of Metastatic Parathyroid Carcinoma in Male C3H Mice Following Irradiation

White nodules were observed in the thyroid in two male C3H mice (at 99 and 122 weeks of age) exposed to fast neutrons at the age of 8 weeks. Histopathologically, in both cases, tumors were developed in the region corresponding to the parathyroid gland, and the tumor cells were arranged in a solid sheet or nest-like structures. Necrosis, cell debris and/or hemorrhage were sometimes seen in the center of the tumor structures. Tumor cells were small and uniform with scanty cytoplasm, cell margins were indistinct, and basally located tumor cells were aligned along the vascular stroma. Mitotic figures were frequently observed. Metastasis to the renal cortex was observed in both cases. These cases were diagnosed as parathyroid carcinoma. A parathyroid tumor is an extremely rare endocrine tumor in mice, regardless of whether the tumor is spontaneous or experimentally induced. These cases may have been induced by neutron-exposure; however, how radiation induces parathyroid carcinoma in mice is not clear.

Update on genetic and clinical aspects of primary hyperparathyroidism

Primary hyperparathyroidism (pHPT) is a common endocrine disorder that predominantly affects postmenopausal women. It is mostly caused by solitary tumours within the parathyroid glands. Although the pathophysiology of pHPT is still incompletely understood, recent studies provide new clues on the development and cellular growth of tumours within the parathyroids associated with hypersecretion of parathyroid hormone and hypercalcaemia. The natural course of pHPT is rather benign. Nowadays, it has become an oligo- or asymptomatic disease often only detected by routine blood tests. These facts raise the question whether to perform parathyroidectomy on oligo- and asymptomatic patients with pHPT or whether it is possible to monitor these patients without surgery. The aim of this article is to review the literature as regards (i) the pathophysiological mechanisms that underlie parathyroid neoplasia and (ii) the defective calcium-sensing in patients with pHPT (iii) environmental and/or genetic risk factors that predispose to or promote parathyroid neoplasia, as well as (iv) alternative approaches to treat oligo- and asymptomatic patients with pHPT medically.

Hyperparathyroidism and subsequent cancer risk in Denmark

BACKGROUND

There is increasing evidence that hyperparathyroidism (HPT), a condition that leads to elevated serum calcium levels, is associated with endocrine and other malignancies, suggesting a possible causal link between HPT and carcinoma.

METHODS

To investigate the relation of HPT to subsequent cancer risk, the authors conducted a record-linkage study among 2425 patients who were diagnosed with HPT in Danish hospitals. Patients were identified in hospital discharge records, and records were then linked with the Danish National Cancer Registry for the years 1977-1993 to identify cancer incidence. To estimate cancer risk, standardized incidence ratios (SIRs) were computed.

RESULTS

After excluding patients who were diagnosed in the first year of follow-up, a total of 219 malignancies were observed, resulting in an SIR of 1.25 (95% confidence interval [95%CI], 1.1-1.4). Cancer risk among women was higher than among men. Among those with primary (idiopathic) HPT, hematopoetic malignancies were elevated significantly (SIR, 1.88; 95%CI, 1.0-3.2; based on 13 patients), with the excess derived primarily from 4 observed patients with multiple myeloma. Patients with secondary HPT had an insignificantly increased risk of overall cancers. Patients who were diagnosed with other or unspecified types of HPT had significant increases in carcinoma of the urinary tract (SIR, 2.71; 95%CI, 1.2-5.3; based on 8 patients) and carcinoma of the thyroid gland (SIR, 21.19; 95%CI, 4.3-61.9; based on 3 patients).

CONCLUSIONS

Future studies should monitor whether specific endocrine alterations associated with HPT may affect the long-term risk of hematopoetic, thyroid, and urinary tract carcinomas.

Late endocrine, metabolic and skeletal sequelae following treatment of childhood cancer

With an ever increasing adult population of childhood cancer survivors there is a need to focus on the late effects of cancer therapy. It is essential that, after discharge from the paediatric oncologists, the patients are not lost from the health system but are under continued surveillance with access to the appropriate physicians. Endocrine and metabolic consequences may affect a patient's life both soon after cancer treatment and also for many years in the future. In this review we consider the following potential problems: growth hormone deficiency and replacement in adulthood, cardiovascular risk factors, osteopaenia, thyroid and parathyroid dysfunction.

Coexistence of primary hyperparathyroidism and thyroid disease

Primary hyperparathyroidism (HPT) and thyroid disease are both relatively common diseases, which can coexist in the same patient. However, mere coincidence does not seem to be a satisfactory explanation for this association. Some factors like prior exposure to radiation may play a role in the association. The aim of this study was to determine the frequency of thyroid disease associated with HPT in 54 consecutive patients who underwent parathyroidectomy in our center from January 1990 to December 1997. Twenty-eight (52%) patients had thyroid disease associated to HPT. The patients had a mean age of 61+/-13 yr; they were predominantly postmenopausal women. Thyroid disease was detected preoperatively in 20 (71%) patients and during the surgical procedure in 8 (29%). Two patients had previous radiation exposure; one of them with papillary carcinoma of the thyroid. Two patients had hypothyroidism. UItrasonography was performed in the majority of patients in their preoperative evaluation. A multinodular goiter was seen to be the most frequent finding (76%). In addition to parathyroidectomy, 23 (82%) patients were also thyroidectomized. In conclusion, patients with HPT showed a high prevalence of thyroid disease, especially in postmenopausal women. Unsuspected thyroid lesions were found with sufficient frequency to warrant careful preoperative and intraoperative evaluation of both glands, in order to obviate reoperation. In experienced hands, combined surgery can be safely performed. Cervical ultrasonography is useful in the preoperative detection of nodular thyroid disease in these patients.

Thyroid carcinoma found at parathyroidectomy: association with primary, secondary, and tertiary hyperparathyroidism

BACKGROUND

Frequent reports of an association between primary hyperparathyroidism (HPT) and well differentiated thyroid carcinoma, compared with the few reports of associated secondary HPT and thyroid carcinoma, may have implications for different etiologic relationships between the conditions.

METHODS

A retrospective review was performed of patients who underwent surgery for HPT between 1975 and 1996 in a single institution. The prevalence of well differentiated thyroid carcinoma diagnosed at the time of parathyroidectomy (PTX) was compared for patients with primary, secondary, or tertiary HPT.

RESULTS

There were 845 operations for HPT in 824 patients. Twenty-two patients were found to have thyroid carcinoma at the time of PTX. Thyroid carcinoma was found in 2.6% of the patients with primary and 3.2% of the patients with either secondary or tertiary HPT (P = 0.550). Twenty-one of the patients had papillary carcinoma and 1 had a follicular carcinoma. Eighteen of the carcinomas were < 1 cm in size. A prior history of head and neck irradiation was associated with the diagnosis of thyroid carcinoma at the time of PTX (P < 0.001). Neither renal failure, organ transplantation, female gender, lymphocytic infiltration, nor follicular adenoma of the adjacent thyroid were significant in the association between HPT and thyroid carcinoma.

CONCLUSIONS

These data suggest that the association between thyroid carcinoma and HPT is coincidental and possibly related to the closer surveillance of the thyroid gland due to PTX and often concomitant removal of thyroid tissue. Patients with HPT and a history of head and neck irradiation are at increased risk of thyroid carcinoma.

Association of hyperparathyroidism with nonmedullary thyroid carcinoma: review of 31 cases

In a series of 948 patients operated on for primary hyperparathyroidism (HPT) by one surgeon (JNA) from 1952 to 1992, there were 242 (26%) instances of coincidental thyroid and parathyroid disease. Of these, 211 had benign thyroid lesions. In the remaining 31 cases HPT was associated with nonmedullary thyroid carcinoma; all were treated by resection of parathyroid adenomas and thyroidectomy. One patient died of unrelated cause (carcinoma of breast) 11 years following surgery. The remaining 30 patients are living and well 2 to 20 (mean 8.2 years) years after surgery; there was no recurrence or thyroid cancer-related mortality in the series. In contrast to prior reports, only six (20%) of our patients had a history of prior radiotherapy. We suggest that during neck exploration for HPT, the entire thyroid gland be evaluated and all palpable nodules resected and submitted to pathologic study.

Parathyroid adenoma in a cancer center patient population

The association of parathyroid adenoma and antecedent events or relationships was examined retrospectively in 103 patients with parathyroid adenoma drawn from a cancer institute patient population. Patients were divided into two study groups by the referral pattern-intramural or community. The major contrast between the two groups was that the intramural patients had cancer diagnoses. The factors of advanced age, female gender, and prior regional irradiation appeared to be associated with the development of parathyroid adenoma. An interrelationship of incidental cancer and parathyroid adenoma, however, was not supported. Breast and differential thyroid cancers were most frequently associated with parathyroid adenoma, but age, gender, and irradiation were bias influences.

Early changes in parathyroid function after high-dose irradiation of the neck

Hyperparathyroidism (HPT) will develop years later in a number of patients irradiated to the neck for benign diseases. Twenty-nine patients with malignant diseases were studied for 3 years after irradiation with cancer therapeutic doses to the neck. The serum concentration of parathyroid hormone (iPTH) showed an increasing trend suggesting that HPT also might develop in these patients.

Differentiated thyroid cancer in children

Differentiated thyroid cancer in children remains a controversial disease entity. Its incidence has markedly declined over the last decade since the use of radiotherapy in the treatment of benign conditions of the head, neck, and thorax was abandoned. Other etiologic factors have become relatively more important. The clinical presentation of childhood thyroid cancer is similar to that found in adults, except for a higher frequency of local and distant metastases at the time of initial diagnosis. The specificity and sensitivity of diagnostic tests are limited; however, like in adults, fine-needle aspiration compares favorably with other available diagnostic methods. The therapeutic approach to a child with thyroid cancer represents the most controversial issue associated with the disease. This review provides a discussion of the rationale for the different therapeutic options and emphasizes the excellent prognosis and survival rates, especially when patients are subjected to aggressive treatment with total thyroidectomy followed by the administration of radioactive iodine.

An assessment of the risk of developing hyperparathyroidism and thyroid disorders subsequent to neck irradiation in middle-aged women

We investigated the occurrence of thyroid and parathyroid disorders in 100 women (age 66-70 years) irradiated for cervical spondylosis on average 25 years previously and in 100 control women of similar age. Hyperparathyroidism (HPT), proven by operation, was diagnosed in one patient of each group, and three additional cases were diagnosed biochemically among irradiated women. The difference in incidence is not significant. Nor was there any significant difference in incidence of thyroid disorders. No thyroid carcinoma was found in either group. Even if there is a moderate increase of HPT after neck irradiation in middle-aged women the risk is not so great as to warrant organised follow-up.

Hyperparathyroidism

A review of hyperparathyroidism and current controversies in diagnosis and management is presented. Accurate diagnosis by the endocrinologist and an experienced surgeon remain the standards for good surgical results. Hyperparathyroidism is a heterogeneous disease, and therapy must be individualized to each patient. Conservative surgical removal of parathyroid tissue is preferred in most patients.

Unchanged parathyroid function following irradiation for malignancies of the head and neck

Irradiation to the neck increases the prevalence of hyperparathyroidism and may cause parathyroid insufficiency. In this study, 35 patients who received therapeutic irradiation to the neck and a control group comprising 19 patients who received radiation to the bladder were studied before, during, and until 2 months after irradiation in order to see whether there were any measurable changes in the parathyroid function. In both groups the serum concentrations of calcium, phosphate and parathyroid hormone were unchanged. Serum protein and albumin decreased in the bladder cancer group. The results support the concept that the parathyroid gland has a low radiation sensitivity, and radiation induced changes may not manifest itself before years after irradiation, due to the low mitotic activity.

Hyperparathyroidism following irradiation of benign diseases of the head and neck

In a series of 73 consecutive patients with hyperparathyroidism (HPT) eight patients gave a history of irradiation of head and neck because of benign diseases. The average interval between irradiation and definite diagnosis was 34 years. Intermittent hypercalcaemia was found in three patients. Microscopic examination of pathologic parathyroid glands of three patients showed a predominance of oxyphil cells. Thyroid abnormalities occurred more frequently in irradiated patients than in nonirradiated patients with HPT. Reviewing clinical and experimental data an etiologic role of irradiation in the pathogenesis of HPT appears present.

Risk factors for thyroid abnormalities after neck irradiation for childhood cancer

Thyroid evaluations were performed in 95 patients who received radiotherapy to the neck region for childhood cancer five to 34 years earlier. Fifty-six patients (61 percent) had at least one abnormality of serum free thyroxine index, serum thyroid-stimulating hormone (thyrotropin), or thyroid palpation. Seven had subnormal free thyroxine index and 40 had elevated thyrotropin concentrations. Thyroidal radiation doses of 3,000 or more rads and lymphangiography independently increased the risk (p less than or equal to 0.01) of an elevated serum thyrotropin concentration (present in 11 percent of patients with neither risk factor, 50 percent of those who underwent lymphangiography and received less than 3,000 rads, 46 percent of those who had 3,000 or more rads and no lymphangiography, and 76 percent of those with both), but duration of follow-up did not. Twenty-six patients had thyroid nodules and six others had diffuse thyroid enlargement. The frequency of palpable abnormalities increased with the follow-up time after radiation (30 percent of patients followed up less than 10 years had abnormalities versus 43 percent of those followed up 10 or more years, p = 0.03), but was not related to the serum thyrotropin level, radiation dose, or lymphangiography. Among 10 patients who had surgery for nodules, three had localized papillary thyroid carcinomas.

Prior irradiation and the development of coexistent differentiated thyroid cancer and hyperparathyroidism

Twelve patients with coexistent well-differentiated thyroid carcinoma and primary hyperparathyoidism were studied to determine the frequency of previous radiation exposure. Eight were found to have received prior irradiation. External radiation was administered to the head and neck region for benign conditions such as tonsillar enlargement, acne, scrofula, and thyroid enlargement. One patient received 131I therapy for carcinoma of the thyroid. The observation that 67% of the patients in this series had previous radiation to the head and neck strongly implicates radiation exposure in the development of coexistent well-differentiated thyroid carcinoma and hyperparathyroidism.

Head and neck neoplasia following irradiation for benign conditions

A retrospective review of 143 patients with head or neck tumors who had received radiation therapy in the head and neck area for benign conditions during childhood or adolescence was conducted. This included an analysis of 1,080 patients from the Evanston Hospital Irradiated Thyroid Evaluation Clinic, which was established to define the relationship between irradiation and the subsequent development of thyroid neoplasia. The data support the following concepts of irradiation-induced neoplasia: (1) The thyroid, parathyroid, and salivary glands can develop benign and malignant changes after irradiation for benign conditions, with latent periods averaging about 30 years; (2) Once a glandular abnormality within the irradiated field appears, the risk of other glands in the field developing neoplastic changes is significantly increased.

Unexpected parathyroid disease discovered at thyroidectomy in irradiated patients

Eight of 23 patients undergoing total thyroidectomy for radiation-associated nodular thyroid disease were found to have unsuspected parathyroid hyperplasia or adenoma at operation. The total serum calcium level was normal preoperatively in each patient. Serum ionized calcium and parathyroid hormone levels were measured in five patients preoperatively and were normal in each case. These pathologic findings in normocalcemic patients may represent a preclinical form of hyperparathyroidism, which would be further evidence linking radiation to the pathogenesis of hyperparathyroidism. The parathyroid glands should be evaluated both pre-operatively and at operation in all patients who have a history of radiation and require thyroidectomy.

Carcinoma of the larynx in childhood

The unusual case of a 12-year-old boy with well differentiated in situ, and focally invasive squamous carcinoma of the larynx is reported, together with a review of the medical literature. In addition to this one, 54 cases of laryngeal carcinoma in children 15 years of age or younger have been reported since 1868. All were squamous except for one adenocarcinoma of a laryngeal minor salivary gland. Carcinoma of the larynx in children parallels that of adults in terms of squamous histology, predominantly vocal cord involvement, pattern of local spread, and response to treatment. However, the incidence of female patients is higher in childhood (40% of childhood cases vs. less than 10% of adult cases), and risk factors, except previous irradiation of papillomas, are rare. Although unusual, carcinoma of the larynx in children is probably more common than thought and the diagnosis should be considered in any case of a child with persistent hoarseness or cough.

Disorders of endocrine function following cancer therapies

There is a growing body of literature detailing the endocrine consequences of cancer therapy. Certain conclusions can be drawn from the data presented. Patients who have received incidental hypothalamic--pituitary gland irradiation need to be followed carefully with serial dynamic hormonal evaluations, as they are at high risk of developing growth hormone and prolactin abnormalities and can develop other pituitary tropic hormone deficiencies as well. Children especially should be monitored closely as GH deficiency can be corrected if detected early. Patients who have received radiation to the head and neck region will need long-term (up to 30 years) surveillance for the development of thyroid cancer, hyperparathyroidism or hypothyroidism. Persistent elevations of TSH after incidental thyroidal irradiation are frequently seen and should be reversed with thyroid hormone administration in an attempt to minimize TSH stimulation of the irradiated gland. Radiation to the gonads will cause graded damage dependent on the dose delivered and the mode of fractionation. Age in a woman seems to be a significant factor of radiation sensitivity. Certain chemotherapeutic agents are radiomimetic in their gonadal effects; to date the alkylating agents have been most commonly implicated. FSH elevations herald gonadal damage (aspermia or loss of follicles) and should be looked for in patients receiving abdominal radiation or systemic chemotherapy. Leydig cell dysfunction occurs less frequently. Of all the iatrogenic endocrine complications discussed, some are eminently treatable, and some are quite preventable. Greater awareness of the unexpectedly high incidence of hormonal dysfunction can help lessen therapy-induced morbidity in long-term cancer survivors.

Irradiation induced salivary gland neoplasia

Twenty-six patients with a prior history of irradiation for benign conditions of the head and neck and salivary gland abnormalities are reported. All the patients had preoperative physical findings suggestive of tumor, not glandular infection. Forty-six per cent of the patients had one carcinoma and 11% had two carcinomas within the irradiated field. Eight of the 11 malignant tumors in these 26 patients were in the parotid gland. The nonmalignant salivery changes were similar to those previously reported in glands receiving therapeutic irradiation for carcinoma.